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LiPo charger IC

Halil Ibrahim Cakar
Prodigy 130 points
Other Parts Discussed in Thread: BQ24083, BQ24165, BQ24115, BQ24100, BQ25070

Dear sir,

I have a Lithium Polymer battery. the battery is single cell, rated  3.7 V and 2350 mAh. I have selected to use BQ24083DRCRG4. I wonder if does this choice fit for my battery or do you have any other stand alone/linear/single-cell battery charger solution for my battery? It is for a portable medical application. Thank you very much,

Very Kind Regards,

Halil Ibrahim

  • 0
    TI__Guru**** 152756 points

    What is your input power supply's voltage and current rating?

  • 0 in reply to Jeff F
    Prodigy 130 points

    Dear Jeff,

    Thank you so much for your answer. Do you ask input power supply for charging circuitry or input voltage and current rating for the remaining device?

    • Designated source input power supply for charging circuitry is 6V.
    • Input power for remaining circuitry is 3.3V
    Very Kind Regards,
    Halil Ibrahim
  • 0 in reply to Halil Ibrahim Cakar
    TI__Guru**** 152756 points

    The bq24083 should meet your needs, assuming that the LiPo battery recommended maximum charge voltage is either 4.06V or 4.2V.  However, keep in mind that at Vin=6V and a discharged battery, the IC will be thermally limited, and charge at a rate less than 1A,  until the battery voltage rises quite a bit.  This means the charge time will be several hours. 

    Have you considered one of our switchmode charges, like bq24115 or bq24165.  They require an inductor but would allow you to charge at a higher charge rate and therefore charge more quickly?

  • 0 in reply to Jeff F
    Prodigy 130 points
    Dear Jeff, I m going to take into account your advices during the design. I have a final question; if I use BQ24100 is it necessary to use 103AT termistor? Thank you so much! Very kind regards, Halil Ibrahim
  • 0 in reply to Halil Ibrahim Cakar
    TI__Guru**** 152756 points

    The TS pin is expecting to be connected to a thermistor but if you don't want to use a thermistor, you can tie the TS pin to fixed voltage through a resistor divider and effectively disable the TS function.

  • 0 in reply to Jeff F
    Prodigy 130 points

    Dear Jeff,

    We are planning to power BQ24100 with USB. According to you is it acceptable?

    Very Kind Regards,

    Halil İbrahim

  • 0 in reply to Halil Ibrahim Cakar
    TI__Guru**** 152756 points

    The bq24100 will work but it does not have some of the latest features for interfacing with USB.  I have forwarded this post to a colleague who might have a better solution.  Can you wait for him to respond by Monday at the lastest to make your final decision?

    Also, can I get some information about the application and your production schedule?  For instance, do you need to power the rest of the circuitry while charging the battery?  When will you start production and what are your production quantities?  We have a part coming out later this year that might work better for you.  I can get samples by end of the month.

  • 0 in reply to Jeff F
    Prodigy 130 points

    Dear Jeff,

    Thank you very much for your solutions for our problem. I will be waiting for the answer coming from your colleague.

    As I mentioned you earlier, our application is a portable medical device. Actually, It is not necessary to power the rest of the circuitry during the charging. But It would be a good feature. This is the prototyping process. In that case, I can not predict the accurate production date and the quantities. However, It ll be as a great experience for us to use a very novel product. Thank you,

    Very Kind Regards,

    Halil Ibrahim

  • 0 in reply to Halil Ibrahim Cakar
    TI__Guru**** 152756 points

    The bq24100 is not the best choice for USB input.  I suggest using the bq24165 or one of its sister parts and ground the IN input. 

  • 0 in reply to Jeff F
    TI__Prodigy 20 points

    You may also consider the bq25070 which is specifically designed to support LiFePO4 charging applications.

  • 0 in reply to Jeff F
    Prodigy 130 points

    Dear Jeff,

    I have settled the suggested reference BQ24100 design for;

    VIN = 5V

    IIN = 500mA

    VBAT = 3.7V

    Safety Charge Timer ~ 85 minutes.

    Everything s ok with the chargment. But, I could not detect that the transistor on the STAT2 pin turned on when the voltage of the battery reached to its Regulation Voltage (3.7V). I mean the LED that is connected to STAT2 did not light when the battery is fully charged. Am I missing somewhere? (I have tested with both USB and Power Supply).

    Thank you very much,

    (As I mentioned that I use the suggested BQ24100 reference design indicated on datasheet page7, Figure-1)

    Very Kind Regards,

    Halil Ibrahim